The extension of brewing production is basically limited by the scope of malt production. This step needs substantial equipment and work and is very energy consuming and it is very hard to develop extensively. Thus, world-wide research has been carried out in the field of intensive development in order to save material and energy and to increase capacity.
Germination is a physiological process which takes place only under controlled conditions in the presence of sufficient humidity, heat and oxygen. By altering these conditions the biological processes may be controlled within certain ranges but these ranges are very limited.
The metabolism of barley can be influenced by plant hormones, natural and artificial inhibitors, as well as by physical methods. Generally, the materials influencing the development of germination may cause stimulation or inhibition depending on the concentration thereof. Many chemicals have been suggested for inhibiting the germination of barley. Kirsop and Pollock, Proc. European Brewery Com., 84, 1957 suggests the use of comarin; Razga in Soripar, 169 (1961) discloses the effect of sodium azide. Potassium bromate may also be used according to Macey and Stowell, J. Inst. Brewing, 63, 391 (1957).Narziss: A sorgyartas, Budapest, 1981 describes the use of nitric acid while Gy. Kollar: Mezogazdasagi Kemia Technologiai Tanszek Kozlemenyck, 1960 suggests the use of phenylacetic acid, 2,4-dichlorophenoxy acetic acid or beta-oxy-phenylacetic acid.
Among the materials stimulating germination the best known is gibberellic acid which results in an enhanced enzyme induction. This enhanced enzymatic effect cannot be controlled, however; thus the malt having been germinated by the addition of gibberellic acid is liable to dissolve to a greater extent than is necessary which can result in enhanced coloring during drying and in an increased malting loss. In order to avoid these unfavourable results, combined methods are used, e.g. the unfavorable effects of gibberellic acid are compenated with potassium bromate.
The chemical methods have the disadvantage that malt contains residues due to the treatment.
It is well known that certain residues have strong influence on the metabolism of plants. These can stimulate or inhibit the development of germ depending on the dose.
Kiss et al., Soripar, 44 to 48 and 81 to 83, 1963 have already examined the influence of ionizing rays on the germination of barley. They came to the conclusion that the dose of radiation essentially did not influence the enzymatic system.